[phobos] Phobos/Druntime to 64 bit

[Walter Bright]

I've gotten Phobos1 to at least pass the semantic phase of compiling 
with -m64. It would be nice if one of you would look at the checkin 
changes, and fold them correspondingly into Phobos2/Druntime. 
http://www.dsource.org/projects/phobos/changeset/1907

You'll need the latest dmd2 executable to build them, though don't 
expect them to get farther than the semantic pass.

Also, the latest zlib apparently supports 64 bit filesystems. The 
existing one does not. It would also be nice if someone would update 
Phobos' version. http://www.zlib.net/

Thanks!